Knit fabrics is one of the oldest and maybe the easiest way of producing a fabric. In a knit fabric the yarns are making loops around each other and this bending results in softer fabrics that have greater volume than standard woven fabrics; knitted fabrics are much softer and more flexible than most of woven fabrics. However the fabric stability (i.e. the keeping of the original shape or “shape retention”) is not as good as in woven fabrics. Therefore knit fabrics are used in topswear like jumpers or sweatshirts or t-shirts or for bottoms in more sportive fields like sweatpants due to their softness and comfortness.
A woven fabric is obtained by crossing weft yarns and warp yarns, in a weaving pattern whereby the weft yarns are extending over and below a number (1 or more) of warp yarns to provide, with respect to the warp yarns, correspondent over portions and under portions. A woven fabric has a face side (or front side) and a back side and the weft yarn floats over one or more warp yarns in the front side of the fabric and subsequently under one or more warp yarns, in the back side of the fabric. Vice versa, a warp yarn can float over or under the weft yarn respectively on the face (or front) side or on the back side of the fabric.
Denim is a popular fabric that is produced by weaving weft and warp yarns in a twill design.
In general, the most common denim fabrics are 3/1, 2/1 weave fabrics, more rarely 1/1 and sateen fabrics. The mentioned number indicates how many connection points there are in the smallest repeat construction unit, or weaving scheme, of warp and weft yarns. Thus, 1/1 means that at each connection the warp yarn is changing its position, namely from upside of the weft (face side of the fabric) to the downside of the weft yarn (back side of the fabric).
A ratio 2/1 means “two up, one down”, i.e. that the weft yarn is floating under two warp yarns and than changing the position from down to up; every 3 weft insertions the warp yarn position is changed once. Similarly, in 3/1 construction every 4 weft insertion there is 1 warp yarn position changing and, in 4/1 every 5 weft insertion the warp yarn changes its position once. When there is a high number of position without changing, i.e. the longer is the length of the weft portion floating under the warp yarns, the looser and softer are the woven fabrics. Within this meaning, 1/1 weave is a fabric stiffer than a 4/1 fabric, in the same condition of remaining parameters such as characteristics of the yarns etcetera.
The most common weaves for denim are 1/1, 2/1 and 3/1, with twill looks; higher numbers of consecutive floating warps, such as 5/1 or higher, do not impart to the fabric the required denim look, while a 4/1 ratio is generally a border-line case.
A well known problem with denim fabrics is that fabrics obtained from 100% cotton yarns may be quite stiff and rigid, so that there is a lack of comfort for the user. To solve this problem denim fabrics have been provided with elastic yarns, usually weft yarns, that reduce stiffness of the fabric and improve wearability of the clothing article, in particular jeans. These fabrics are called “stretch woven fabrics” or “stretch fabrics”.
Stretch fabrics have been known and manufactured for many years. In these known fabrics, the elastic yarn provides the elasticity required for the fabric to stretch and to recover the stretched portion. Because the elastic yarn is part of the fabric, in particular it can be the weft yarn, it is required that it does not compromise the aspect and the look of the fabric. To this purpose, the elastic yarns often include a core made of an elastomer and a cover for the core that is made of inelastic fibers, generally cotton fibers, so as to mimic the appearance of a standard, non-elastic, 100% cotton yarn.
There are known several tentative solutions for the problem of providing an elastic yarn having a satisfactory aspect notwithstanding the inclusion of elastomeric core; some of them are satisfactory, such as the solution disclosed in PCT application PCT/EP2011/005723 in the name of the present applicant.
WO2011104022, in the name of the present applicant, discloses a woven fabric in which the weft yarns are made by first yarns and second yarns that are different and that are woven with different patterns. The first yarns are less elastic that the second yarns and are woven with very long under portions so that when the fabric shrinks because of the action of the second yarns, that are more elastic than the first yarns, the long under portions of the first yarns provide a plurality of loops on the back side of the fabric and of the clothing garment obtained from the fabric.
However, a problem with known stretch fabrics is that they look too flat with respect to non-elastic fabrics, i.e. they have a two-dimensional appearance.